1. Field of the Invention
The present invention relates to a light emitting polymer composition suitably usable as an organic electroluminescence material, and an organic electroluminescence device and a production process thereof.
2. Description of the Background Art
An organic electroluminescence device is expected as a display device of the next generation because it has such excellent properties that it can be provided in a thin form, driven by direct current voltage, and is wide in angle of visibility, high in visibility and fast in the speed of response, and researches thereof are being actively conducted.
As organic electroluminescence devices, there have heretofore been known those of a single-layer structure that a light emitting layer composed of an organic material is formed between a positive electrode and a negative electrode and those of a multi-layer structure such as a structure having a hole transport layer between a positive electrode and a light emitting layer and a structure having an electron transport layer between a negative electrode and a light emitting layer. In all of these organic electroluminescence devices, light is emitted by recombining an electron injected from the negative electrode with a hole injected from the positive electrode at the light emitting layer.
As processes for forming functional organic material layers such as the light emitting layer and hole transport layer in such an organic electroluminescence device, there have been known a dry process that an organic material layer is formed by vacuum deposition and a wet process that a solution with an organic material dissolved therein is applied and dried to form a layer. Among these, the dry process is difficult to meet mass production because the process is complicated, and there is a limit to the formation of a large-area layer. On the other hand, the wet process can meet mass production because the process is relatively simple. In addition, a large-area functional organic material layer can be easily formed. In these respects, the wet process is useful compared with the dry process.
On the other hand, the functional organic material layer making up the organic electroluminescence device is required to have high durability and achieve high luminous efficiency. Those composed of various materials have heretofore been known, and functional organic material layers containing a phosphorescent organoiridium compound or organoosmium compound as a luminous molecule have recently been proposed (WO 00/70655). Such a functional organic material layer is formed of the organoiridium compound or organoosmium compound alone or of such a compound and a hole transport material such as 4,4′-N,N′-dicarbazole biphenyl or 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl.
However, this functional organic layer is formed by the dry process, and so it is difficult to meet mass production and form a large-area functional organic material layer.
A light emitting material composed of an iridium compound, polyvinylcarbazole and oxadiazole has been proposed in MRS 2000 Fall Meeting (Nov. 27 to Dec. 1, 2000, Boston, Mass., USA).
However, this light emitting material involves a problem that it is poor in durability though it has high luminous efficiency.